Associations of Pregnancy History with BMI and Weight Gain in 45–54-Year-Old Women

BACKGROUND: Midlife women have a higher risk of cardiometabolic disease than younger women, but the lifelong biological/lifestyle factors responsible for this increase are unclear. OBJECTIVES: We investigated whether pregnancy history is a risk factor for midlife overweight/obesity and evaluated potential hormonal mechanisms. METHODS: The Baltimore Midlife Women's Health Study, a prospective cohort, recruited 772 women aged 45-54 y. Women reported pregnancy characteristics via questionnaires, trained staff measured weight/height to calculate midlife BMI, and serum hormones were assessed by ELISA. Logistic regression models assessed associations of pregnancy history with risk of midlife overweight/obesity and BMI gain since age 18. We additionally explored whether associations differed by menopausal status, and whether midlife hormones mediated relationships of pregnancy history and midlife BMI. Number of pregnancies and age at last pregnancy were not associated with midlife overweight/obesity or BMI gain. Associations did not differ by menopausal status and were not explained by midlife hormones. CONCLUSIONS: Earlier childbirth and having 1 child increased women's risk of midlife overweight/obesity and BMI gain since age 18. Additional studies should focus on women's childbearing years as a critical determinant of midlife metabolic health.